1. Field of the Invention
This invention relates to a temperature distribution measuring instrument for obtaining a thermal image of an object by detecting infrared rays from the object such as a human body. More specifically, it relates to a temperature distribution measuring instrument for obtaining a two-dimensional thermal image of an object to be measured using a single-element type infrared sensor.
2. Description of the Prior Art
A temperature distribution measuring instrument 1 of the prior art which uses an infrared sensor array for detecting infrared rays from an object to be measured, such as a human body, converges infrared rays from the object at a sensor array 7 by a condenser lens 6 when a slit 3s formed in a side portion of an inner cylinder 3 rotated by an inner cylinder drive unit 2 is aligned with one of a plurality of slits 4s formed in a side portion of an outer cylinder 4 and measures the temperature distribution of the object 5 as shown in FIG. 17. FIGS. 18(a) and 18(b) are perspective views of the inner cylinder 3 and the outer cylinder 4, respectively. Out of infrared rays passing through 16 slits 4s in the outer cylinder 4, only infrared rays which are aligned with the slit 3s in the rotating inner cylinder 3 are input into the sensor array 7 as shown in FIG. 18(c), and a voltage corresponding to the intensity of the infrared rays from the object 5 is output from the infrared sensors 7A (7AA to 7AE) of the sensor array 7. For the temperature compensation of the output of the infrared sensor array 7, as shown in FIG. 18(b), a thermister 8 is provided on a lower end portion of the side of the inner cylinder 3. The slit 3s in the rotating inner cylinder has chopping and scanning functions to transmit and cut off input infrared rays. Infrared rays from the object 5 are input into the sensor array 7 and cut off repeatedly at a frequency (chopping frequency) corresponding to the rotating speed of the inner cylinder 3. A thermal image of the object which is divided into 16 regions corresponding to 16 slits in the outer cylinder 4 in a longitudinal direction and 7 regions A to H corresponding to 7 infrared sensors 7A of the sensor array 7 in a transverse direction as shown in FIG. 19 is obtained. In the figure, black vertical line regions BL are regions where the slit in the inner cylinder does not overlap with the slits in the outer cylinders during the rotation of the inner cylinder.
In the above array type infrared sensor used in the prior art, there have been great differences in performance among infrared sensor elements and it has been difficult to manufacture a sensor array having uniform sensitivity among sensor elements. Therefore, as there have been differences in sensitivity among sensors in a temperature distribution measuring instrument using an ordinary sensor array, it has been difficult to obtain an accurate thermal image unless sensitivity was corrected for each sensor. Further, since it has been difficult to provide uniform performance and high sensitivity to the sensor elements of a sensor array, the temperature distribution measuring instrument of the prior art could not be reduced in size.